Work is the product of the force and the displacement in the direction of the force
One joule is the work done by a force of one newton applied via a displacement of one meter in the direction of the force
The area beneath a force-displacement graph represents the work done
Energy is the ability to do work and, like work, is measured in joules
Energy can be stored, transfered from object to object, and converted from one form to another
Energy is measured in terms of the work done
Gravitational potential energy depends on mass, gravitational field intensity, and vertical height
Kinetic energy depends on mass and speed
According to the law of conversation of energy, energy is neither created nor destroyed
Definitions:
chemical energy: Potential energy stored in molecules
elastic energy: Energy stored in an object when it is forced out of its normal shape
electrical energy (Ee): Energy associated with moving electrical charges
energy (E): Ability to do work
gigajoules (GJ): One billion joules (J)
gravitional energy: Energy associated with the gravitational field.
heat energy: Energy that is transferred by a difference in temperature
joule (J): Work done by a force of one newton applied via a displacement of one metre in the direction of the force; one joule equals one newton x meter
kilojoule (kJ): One thousand joules.
kilowatt hour: kW x h, common unit for electrical energy based on the relation deltaE= P x deltat where power is measured in kilowatts and time in hours; 1kW x h = 3.6 mega joules (MJ)
kinetic energy (Ek): Energy of a moving object.
law of conservation of energy: Energy cannot be created or destroyed; it can be changed from one form to another, but the total amount of energy in the universe stays constant.
megajoule (MJ): One million joules
nuclear energy: Energy stored in the nucleus of an atom
potential energy: The energy of a bodyor system as a result of its position in anelectric, magnetic, or gravitational field.
radiant energy: Energy that travels as electromagnetic waves
relative gravitional energy:
rest mass energy:
sound energy: Energy that is carried from molecule to molecule by longitudinal vibrations
thermal energy: Sum of the potential energy and the kenitic energy possessed by the molecules of an object
work (W): Product of the magnitude of the applied force and the displacement of the object in the direction of the force
Formulas:
Work = (magnitude of the force in the direction of the displacement)
x(magnitude of the displacement) W = Fcos 0 deltad
F is the magnitude of the force
deltad is the magnitude of the displacement
0 is the angle between the force and the displacement
If the applied force is in the same direction as the displacement then the angle 0 is zero, if this is the case then the formula is simplified into W = F deltad
The SI unit of the work is in newton metre (N.m), One joule (J) is work done by a force of one newton (N) applied via a displacement of one meter in the direction of the force: 1J = 1N.m
(Ex. 3) If objects are raised or lowered, the gravitional field intensity (9.8 N/kg [down]) comes into play. A force equal in magnitude to the force of gravity is needed to lift or lower the box at constant velocity. The magnitude of the force of ravity on the box is given by the eq'n FG = mg
W = FGdeltad, W = mg deltad
Rest Mass Energy
It is the total energy that an object has because of its mass. Einstein's theory of relativity indicates that mass is a form of energy. This means that any mass has energy simply because the mass exists. The total energy of a mass at rest is given by the eq'n E = mc2 (squared)
E is the energy in joules, m is the mass in kilograms, and c is the speed of light in m/s
(P. 159)
The work done on a mass is W = F deltad, W = FG deltah, W = mg deltah
Assuming no friction, the work done is equal to the change in gravitional energy. Thus, the eq'n for the change in gravitational energy is deltaEG = mg deltah
Where m is the mass of the object in kilograms
g is the gravitational field intensity in newtons per kilogram
deltah is the magnitude of the vertical displacement of the object in metres
deltaEG is the change in gravitational energy of the object in joules
Kenitic Energy (P. 163)
W = ma deltad
W = m(v2/deltat) (v2/2)deltat W = 1/2m(v2)2 (squared) EK = 1/2mv2 (squared) - m is the mass of the object in kilograms, v is the velocity of the object in metres per seacond, EK is the kenetic energy of the object in joules
(Ex. 11) Conservation of energy= deltaEK = deltaEG and solve for v
Chapter 4 Review
By: Faraz Qazi
Facts:
Definitions:
chemical energy: Potential energy stored in molecules
elastic energy: Energy stored in an object when it is forced out of its normal shape
electrical energy (Ee): Energy associated with moving electrical charges
energy (E): Ability to do work
gigajoules (GJ): One billion joules (J)
gravitional energy: Energy associated with the gravitational field.
heat energy: Energy that is transferred by a difference in temperature
joule (J): Work done by a force of one newton applied via a displacement of one metre in the direction of the force; one joule equals one newton x meter
kilojoule (kJ): One thousand joules.
kilowatt hour: kW x h, common unit for electrical energy based on the relation deltaE= P x deltat where power is measured in kilowatts and time in hours; 1kW x h = 3.6 mega joules (MJ)
kinetic energy (Ek): Energy of a moving object.
law of conservation of energy: Energy cannot be created or destroyed; it can be changed from one form to another, but the total amount of energy in the universe stays constant.
megajoule (MJ): One million joules
nuclear energy: Energy stored in the nucleus of an atom
potential energy: The energy of a body or system as a result of its position in an electric, magnetic, or gravitational field.
radiant energy: Energy that travels as electromagnetic waves
relative gravitional energy:
rest mass energy:
sound energy: Energy that is carried from molecule to molecule by longitudinal vibrations
thermal energy: Sum of the potential energy and the kenitic energy possessed by the molecules of an object
work (W): Product of the magnitude of the applied force and the displacement of the object in the direction of the force
Formulas:
Work = (magnitude of the force in the direction of the displacement)
x(magnitude of the displacement)
W = Fcos 0 deltad
- F is the magnitude of the force
- deltad is the magnitude of the displacement
- 0 is the angle between the force and the displacement
- If the applied force is in the same direction as the displacement then the angle 0 is zero, if this is the case then the formula is simplified into W = F deltad
The SI unit of the work is in newton metre (N.m), One joule (J) is work done by a force of one newton (N) applied via a displacement of one meter in the direction of the force: 1J = 1N.m(Ex. 3) If objects are raised or lowered, the gravitional field intensity (9.8 N/kg [down]) comes into play. A force equal in magnitude to the force of gravity is needed to lift or lower the box at constant velocity. The magnitude of the force of ravity on the box is given by the eq'n FG = mg
W = FGdeltad, W = mg deltad
Rest Mass Energy
It is the total energy that an object has because of its mass. Einstein's theory of relativity indicates that mass is a form of energy. This means that any mass has energy simply because the mass exists. The total energy of a mass at rest is given by the eq'n E = mc2 (squared)(P. 159)
The work done on a mass is W = F deltad, W = FG deltah, W = mg deltah
Assuming no friction, the work done is equal to the change in gravitional energy. Thus, the eq'n for the change in gravitational energy is deltaEG = mg deltah
Kenitic Energy (P. 163)
W = ma deltad
W = m(v2/deltat) (v2/2)deltat
W = 1/2m(v2)2 (squared)
EK = 1/2mv2 (squared) - m is the mass of the object in kilograms, v is the velocity of the object in metres per seacond, EK is the kenetic energy of the object in joules
(Ex. 11)
Conservation of energy= deltaEK = deltaEG and solve for v
Kinematics= deltad = 1/2g(deltat)2 (squared), deltat = square root 2 deltad/g, v2 = g deltat